This invention relates to a process for manufacturing a liquid crystal display element of a simple matrix system, particularly to a process for forming light-shielding layers for making color stripes colored in predetermined colors display each color per picture element unit.
In a liquid crystal display element of a simple matrix system, a TN system or a STN system is used. In either system, transparent electrodes formed on two transparent substrates, respectively, are stripe-shaped. The respective stripe-shaped electrodes are arranged so that they cross at right angles through liquid crystal enclosed therebetween (when stripes arranged in one direction correspond to row, stripes arranged in the other direction correspond to column) . By giving signal voltage to row stripe electrodes and giving scanning voltage to column stripe electrodes, liquid crystal at a portion where the signal voltage is synchronized with the scanning voltage is actuated and displayed. When color display is carried out, a color filter is used. In general, a color filter is inserted between a transparent substrate and transparent electrodes. That is, a color filter is formed on a transparent substrate, and then transparent electrodes are provided thereon.
Particularly in the case of the STN system, it is necessary to form transparent electrodes on a completely smooth surface, so that a top coat layer for smoothing is provided on a color filter layer.
As color arrangement of a color filter, there may be generally used mosaic type color arrangement, stripe type color arrangement, triangle type color arrangement and 4 picture elements arrangement type color arrangement. In the case of a simple matrix system of TN or STN, stripe type color arrangement (said arrangement comprises red, green and blue stripes, and the respective stripes are separated by black light-shielding layers) is used.
In stripe type color arrangement, there is no trouble in displaying letters and figures. However, in the case of displaying an image, color tone and sharpness are poor as compared with mosaic type color arrangement or the like. In order to make image quality close to that of mosaic type color arrangement, light-shielding layers are set in the respective red, green and blue stripes per picture element unit so that the respective picture elements are surrounded with the light-shielding layers. Thus, colors are made conspicuous by surrounding the respective picture elements with black color to greatly improve image quality as compared with color display of conventional stripe type color arrangement, although color arrangement of stripe type color arrangement in which same colored picture elements are arranged in one direction, is different from color arrangement of mosaic type color arrangement in which the respective red, green and blue picture elements are surrounded with black color. However, in preparation of a color filter using stripe type color arrangement, it is a complicated step to set light-shielding layers in the respective stripes per picture element unit, and also it is necessary to carry out perfect positioning with counter electrodes (scanning electrodes in this case) and carry out steps such as mask alignment in which accuracy is required.
If light-shielding layers can be provided at a side of a substrate opposite to a substrate on which a color filter is provided, such a step is much easier than a step of directly setting shielding layers in color stripes, because it is sufficient to provide light-shielding layers between the respective stripes of a transparent conductive film formed in a stripe state as scanning electrodes. In this case, light-shielding layers are provided between the stripes generally by coating a colored light-sensitive resin on a transparent conductive film, carrying out steps of exposure using a mask and development and then removing an unnecessary resin. However, in this case, mask alignment is absolutely necessary, so that the above steps are still complicated to lower yield, which might be a reason for increase in cost.
The present invention has been made in order to solve the problems of the prior art as described above, and an object of the present invention is to provide an easy manufacturing process for manufacturing a color liquid crystal display element in which light-shielding layers are formed for making color stripes colored in predetermined colors display each color per picture element by providing light-shielding layers between the respective stripes of a transparent conductive film formed in a stripe state as scanning electrodes.
The process of the present invention comprises a step of forming a transparent conductive film on one side of one transparent substrate; a step of patterning the above transparent conductive film by coating a colored positive type resist on the above transparent conductive film and then carrying out exposure and development; a step of further coating a black-colored negative type resist thereon without peeling the above resists remaining after patterning; a step of forming black stripes between the above patterned transparent conductive films by subjecting the above negative type resist to exposure from a back side thereof through the above transparent substrate and to development; and a step of peeling the positive type resists remaining on the above patterned transparent conductive films (first process).
Further, the process of the present invention may comprise a step of forming a transparent conductive film on one side of one transparent substrate; a step of patterning the above transparent conductive film by coating a positive type resist on the above transparent conductive film and then carrying out exposure and development; a step of further injecting a black-colored resin between the above patterned resists without peeling the above resists remaining after patterning; a step of forming black stripes between the above patterned transparent conductive films by setting the above resin; and a step of peeling the above resists remaining on the above patterned transparent conductive films (second process). Here, as the above resin, a resin containing a photosetting resin or a thermosetting resin is used.